The present invention relates to a transistor assembly and a method for manufacturing the same, and particularly to an assembly of a power transistor, or the like, using a nitride semiconductor and a method for manufacturing the same.
A nitride semiconductor such as gallium nitride (GaN) has a greater bandgap, a greater breakdown electric field and a greater electron saturated drift velocity as compared with silicon (Si), gallium arsenide (GaAs), etc. In a hetero structure between aluminum gallium nitride (AlGaN) and gallium nitride (GaN), a 2-dimensional electron gas (2DEG) is generated at the hetero interface due to spontaneous polarization and piezo polarization, thereby obtaining a sheet carrier concentration of 1×1013 cm−2 or more without impurity doping. High electron mobility transistors (HEMTs) using the high-concentration 2-dimensional electron gas as a carrier have been attracting public attention in recent years, and HEMTs of various structures have been proposed in the art (see, for example, S. Arulkumaran, et al., “Enhancement of breakdown voltage by AlN buffer layer thickness in AlGaN/GaN high-electron-mobility transistors on 4 in. diameter silicon”, APPLIED PHYSICS LETTERS, 2005, vol. 86, P. 123503).